1. Field of the Invention
This invention relates to a drive mechanism for the component placement head of an automatic electrical component assembly machine.
2. Summary of the Prior Art
In the art of automatically applying electrical components to a printed circuit board, the components are supplied to the placement head of the machine in a desired sequence for placement on the board. The components may be in a reel in which the component leads are taped to present the components in a taped series to the placement head. The placement head contains a mechanism to sever the component leads from the tape, form the leads at a right angle to the component body and insert the leads into preselected openings in the board. Thereafter, a cut-clinch mechanism cuts and forms the leads protruding through the board undersurface to lock the component to the board. Machines of this type are disclosed in U.S. Pat. Nos. 3,488,672, 3,594,889, 4,080,730 and 4,464,833.
Other assembly machines have placement heads that are adapted to receive DIP type components from a source and insert the leads of the component into the openings in the board. In like fashion, a cut-clinch mechanism will secure the component to the board. Machines of this type are illustrated in U.S. Pat. No. 3,550,238.
In the operation of these machines, there is a vertically driven placement head which travels from a position to receive the component from the source to a position to insert the component leads into the opening in the board. The mechanism to vertically reciprocate the placement head has, in the past, been a pneumatic cylinder arrangement (such as illustrated in U.S. Pat. No. 2,896,213) which drives a linkage causing the placement head to move up and down. Because of the varying depth to which the placement head must travel due to the varying diameter of the components being inserted (see U.S. Pat. No. 3,594,889) and the different diameter of the leads, the prior pneumatically driven mechanisms have required an automatically adjustable depth stop to control the depth at which the placement head will move toward the board, for any given component being inserted. An example of such a depth stop is shown in U.S. Pat. No. 4,553,323.